Recovery of vanadium values from an alkali metal vanadate solution



Patented Nov. 27, 1951 RECOVERY OF VANADIUM VALUES FROM AN ALKALI METAL VANADATE SOLUTION Sandford Stoddard Cole, Metuchen, and John Stuart Breitenstein, Linden, N. J assignors to National Lead Company, New York, N. Y., a

corporation of New Jersey No Drawing. Application October 11, 1949, Serial No. 120,826

4 Claims.

1 This invention relates to the process for the recovery of the vanadium values from an alkali metal vanadate solution. More specifically, it relates to a process for the recovery of the vanadium values as a complex calcium vanadate 2 from less than 1 to up to about grams per liter vanadium in the alkali metal vanadate solution.

The precipitating agents used in the present process are hydrated lime and calcium chloride. Both agents are necessary when precipitating the precipitate. 5 vanadium values from solutions within this pH The recovery of vanadium values from various range in order to obtain high recoveries. The types of ores or concentrates is a difiicult and employment of either hydrated lime or calcium complicated problem. Many types of processes chloride alone or used singly without the presence have been proposed and utilized. One such procm of the other agents produce low recoveries. The ess involves roasting the ore or concentrate at presence of the two precipitating agents produces elevated temperatures in the presence of alkali a synergistic effect in the precipitation of the vametal salts and subsequently leaching the roasted nadium values and high yields, 1. e. greater than material to solubilize the so-formed alkali metal 99%, have been obtained by this process. The vanadate therefrom. The present invention em- 1,; amount of agents necessary is not critical and braces a process for the recovery of the vanadium may vary considerably, but for efficient results it values from such an alkali metal vanadate sohas been found that for each part of vanadium lution. present in the alkali metal vanadate solution, it An object of the present invention therefore is is necessary to add at least 0.3 part of calcium to present an economical process which precipichloride and at least 2.0 parts of hydrated lime; tates substantially all of the vanadium values while the preferred range to obtain high yields froman alkali metal vanadate solution. Another with minimum quantity of precipitating agents object is to utilize inexpensive precipitation requires from 0.4 part to 2.0 parts of calcium agents in the recovery of the vanadium values. chloride and from 2.0 parts to 4.0 parts of hy- These and other objects will become apparent drated lime. The agents are preferably mixed from the following more complete description of with Water and added in solution or slurry form the invention. to the vanadate solution but the dry agents may It has been discovered by the process of this inbe added if desired. vention that substantially all of the vanadium The reaction is preferably carried out at room values may be recovered from an alkali metal temperature and therefore a considerable saving vanadate solution having a pH of 7.5 to 8.5 by in heating costs is attained over other proceesses treating said solution with calcium chloride and which require elevated reaction temperatures. hydrated lime to precipitate and separate a com- The time of reaction is fairly rapid to obtain good plex calcium vanadate composition therefrom. yields, e. g. 20 to 30 minutes are used for labora- According to this process it is preferred to use tory scale batches while 1 to 3 hours are used on a vanadate solution which has a pH of 7.5 to 8.5 to large scale batches. The precipitate obtained is obtain the most favorable benefits of this process. bulky and easily filtered and washed. Apparent- If vanadium solutions are employed which lie ly the complex calcium vanadate composition is above pH of 8.5, the solution preferably should be insoluble in water and therefore may be washed adjusted with acidic reagents to lower the pH to with Water Without encountering any washing fall within this preferred range before carrying difficulties. To further illustrate the present in out the precipitation of the vanadium values. vention, the following examples are presented to Most processes for the recovery of vanadium reshow a preferred embodiment thereof: quire the employment of solutions containing relatively high concentrations of vanadium, to EXAMPLE I obtain high recoveries of the vanadium values, A sodium vanadate solution was prepared by but the proceess of the present invention is not reroasting a magnetite ore wi'.h sodium chloride. stricted to such concentrated solutions but may 3 pa ts o S d u Chloride Were intimately miXed be used with equal effectiveness on dilute solutions with 100 parts of a finely-ground, vanadium-concontaining small quantities of vanadium, e. g. taining magnetite ore. The mixture was then roasted in a rotary kiln under an oxidizing atmosphere at 900 C. for 2 hours. The roasted ore was then leached with water at room temperature under counter-current leaching conditions to produce the sodium vanadate solution. The solution contained 4.9 grams per liter of vanadium and had a pH of 8.0.

To this sodium vanadate solution were added at room temperature 0.5 part of calcium chloride (as a %}solution) and 2.1 parts of hydrated lime (as a 10% calcium hydroxide slurry) for each-part of vanadium present in the solution. The treated solution was then stirred at room temperature for minutes, after which the white; complex calcium vanadate composition was separated from the mother liquor by filtration. The precipitate was washed thoroughly with-water toremove the adhering liquor. The 'analysis of) the products showed the recovery of the vanadium values to be 99%.

EXAMPLE II A sodium vanadate solution was prepared in the same manner as.- ;described in Example I except 10 parts of sodium carbonate plus 5 parts ois'odium chloride were mixedgwith 100 parts of vanadium-containing magnetite'ore. The leached solution contained 5.0 grams per liter vanadiumandhad a pH of 9.1. To this solution were added a 10% sulfuric acidsolution inan.

. again 99%.

1 EXAMPLE III Example I was repeated-using -0.5--part'-of calcium chloride and 3.3 parts -of--'-hydrated lime. Again the vanadium recoverywas 99%.

By the process of this invention, high-*yields are obtained as shown in the -examples.- If the precipitation is carried out with solutions having higher pH- values than 8.5, the-yield of vanadium falls offrapidly as 'thepH values -'-areincreased. For this reason, such excessively alkaline solutions should first be partially neutralized to fall within the preferred pH range-of 7.5.to8.5.

When precipitating vanadiumirom an alkali metal vanadate solutionwith calcium compounds according to Ithis inventionboth calcium chloride and calcium hydroxide must beemployed. :Employment of. these agents in combination results in a synergistic efiectthereby. producing exceptionally high yields. .When the precipitating agents are used separately. or. individually, even though added in amounts :equal to the. calcium content of the-:combinationof. agents, therecoveryof vanadium is veryqlowas shown inv the table. The comparative runs .were'carried out according tothe process described in- Example I:

Table GlgrS dof Agents e per grams of Vanadium g ggi 5 Present dium covery CaClz Ca(OH)z Example I 0. 5 2.1 99 Comparative Run #l 5.4 0.0 67 ComparativeRun #2 0. 0 3.. 9 60 By use of the present process exceptionally 'rhigh yields of the-vanadium values are obtained ,15. directly; from-an alkali metal vanadate solution and very dilute solutions may be utilized with equalefiectiveness. The precipitated complex gcalcium vanadate composition is bulky and is .easily'filte'red'oiij and washed. The cost of the operation'is inexpensive since the precipitation iscarried'out at room temperature with the use -o't'inexpensive precipitating agents.

-While this invention has been described and illustrated by the examples shown, it is not intended .to be strictly limited thereto and other variations and modifications may be employed within the .scope' ofJthe following claims.

We claim:

1. A process for the recovery or -vanadium values from an alkali metal vanadate solution having a pH from 7.5 to 8.5 which comprises treating said solution with calcium. chloride and hydrated limej'and precipitating and separating. a'complex calcium vanadate composition therefrom.

2.,A process. for the recovery of vanadium values fr'oman alkali'metal vanadate solution whichcomprises adjusting the pH ofjthe. solution to 7.5-8.5, treating ,said solution with calcium chloride .and hydrated lime, precipitating and separating a complex calcium vanadatecomposi- .tion therefrom.

31 Process according toclaim 1 in 'vvhichfor .every part .of vanadiumpresentin the sodium yanadatefsolution at'least 0.3 partofcalcium I chlorideiand at least 2.0 partsof hydratedlime are. added to-pre'cipitate said 1 complex .Icalcium vanadate composition.

4. Process according .to', claim 1, in .whichfor every part of' vanadium present in the sodium vanadate solution. from 0.4' part. to .2.0 parts,of calcium" chloride and from 2.0 parts. to' 4.0 parts of hydrated lime areadded to precipitatesaid "complex calcium vanadate composition.

,SANDFORD "STODDARDZ COLE. JOHN STUART BREITENSTEIN.

i REFERENCES CITED The following references are of record in the file' of this? patent: 

1. A PROCESS FOR THE RECOVERY OF VANADIUM VALUES FROM AN ALKALI METAL VANADATE SOLUTION HAVING A PH FROM 7.5 TO 8.5 WHICH COMPRISING TREATING SAID SOLUTION WITH CALCUIM CHLORIDE AND HYDRATED LIME AND PRECIPITATING AND SEPARATING A COMPLEX CALCIUM VANADATE COMPOSITION THEREFROM. 